The present invention relates to high-speed imaging, and more particularly to a high-speed three-dimensional imaging system and method that captures digital images in real time.
High-speed three-dimensional (3D) imaging is an increasingly important function in advanced sensors in both military and civilian applications. For example, high-speed 3D capabilities offer many military systems with greatly increased capabilities in target detection, identification, classification, tracking, and kill determination. As a further example, real time 3D imaging techniques also have great potential in commercial applications, ranging from 3D television, virtual reality, 3D modeling and simulation, Internet applications, industrial inspection, vehicle navigation, robotics and teleoperation, to medical imaging, dental measurement, apparel and footwear industries.
In conventionally known 3D imaging systems and techniques, however, the system can only measure a single point or single line on the surface of object or objects being imaged. These systems cannot be used for real-time full frame 3D imaging applications because they often employ a scanning laser beam or laser sheet and an image sensor (e.g., a CCD) to record the locations of the surface points illuminated by the laser. The 3D coordinates on the single spot or multiple points along the line illuminated by the laser can be obtained using a simple triangulation.
To obtain a full-frame 3D image using traditional scanning laser methods, a spot-by-spot or line-by-line scanning process is required, which tends to be inefficient and time-consuming. This type of 3D imaging also has the potential of introducing large measurement errors when the objects to be measured are moving during the scanning process. These systems are therefore unsuitable for high-speed 3D imaging applications because they cannot provide full-frame 3D images in real time at a video rate (e.g., at least 30 frames per second).
There is a need for a high-speed 3D imaging system that can obtain full-frame 3D images in real time. More specifically, there is a need for a system that can obtain the value of each picture element (i.e., pixel) in a captured digital image that represents the physical distance between the focal point of the imager and the corresponding surface point on objects in a scene, thereby allowing calculation of the (x,y,z) coordinates of all of the surface points viewed by the imager based on the 3D image data and the optical parameters of the imager""s geometry.
Accordingly, the present invention is directed to a system and method for high-speed generation of three-dimensional images of a scene. The system includes a light source, such as a laser, that projects a spatially varying intensity light pattern onto the scene to illuminate the scene. A camera captures images of the illuminated scene, and a processor calculates distances to points in the scene corresponding to pixel in an image from the camera by matching intensities with projection angles.
In one embodiment, the scene is illuminated with an even pattern and an odd pattern, each of which have different intensity distributions across the scene. The camera then captures an even image field and an odd image field corresponding with the even pattern and odd pattern, respectively, such that the even and odd image fields together form one complete image frame.
Illuminating a scene to be imaged with a spatially varying intensity light pattern allows the inventive system to capture full-frame 3D images in a single snapshot. Further, because the inventive system can capture images at a high speed, the system can capture successive images in real time, if desired.